There is a conventional steering damper attachment structure in which a steering damper is attached to a head pipe on the vehicle body frame side, and to a bottom bridge constituting a front fork (for example, see Japanese Patent Application Laid-open Publication No. 2005-96735).
The conventional steering damper attachment structure will be described with reference to Japanese Patent Application Laid-open Publication No. 2005-96735.
A cylindrical damper is constituted of a damper case and a damper rod that is slidably disposed to move in and out of the damper case. The upper end of the damper case is rotatably joined with a spherical joint, to a stay extending frontward from a head pipe. The lower end of the damper case is rotatably joined with a spherical joint, to a stay extending frontward from a bottom bridge. The cylindrical damper is also arranged in front of the head pipe, and substantially along the longitudinal direction of the head pipe.
The center axis of the cylindrical damper is substantially perpendicular to the axis extending along the longitudinal direction of each of the stays. Accordingly, each of the spherical joints is in a stationary state at the center of the rotation range thereof. When the handlebar is turned from this state, the stay on the bottom bridge side rotates. In conjunction with the rotation of the stay, each of the spherical joints rotates from the center of the rotation range. If the maximum angle on each side of the rotation range of the spherical joints is smaller than the maximum angle on the side of the steering range of the handlebar, the steering angle of the handlebar is restricted by the rotation range of each of the spherical joints.
Increasing the rotation range on each side of each of the spherical joints makes it possible to increase the steering angle of the handlebar. An object of the present invention is to further increase the steering angle of a handlebar.
An embodiment of the present invention provides a steering damper attachment structure for a vehicle. The structure includes a steering stem, a steering-side member, a vehicle-body-side member, and a steering damper. The steering-side member rotates about the steering stem in conjunction with the operation of a handlebar. The vehicle-body-side member does not rotate in conjunction with the operation of the handlebar. The steering damper is provided between the steering-side member and the vehicle-body-side member. In this structure, in a state where the steering angle of the handlebar is zero, the axis of the steering damper forms an obtuse angle relative to the axis of an attachment portion of the steering-side member to which the steering damper is attached.
Furthermore, in a state where the steering angle of the handlebar is zero, the axis of the steering damper forms an obtuse angle relative to the axis of an attachment portion of the vehicle-body-side member to which the steering damper is attached.
The operation of the present invention will be described below. In a state where the steering angle of the handlebar is zero, the axis of the steering damper forms an obtuse angle with the axis of an attachment portion of the steering side member to which the steering damper is attached. In this case, when the handlebar is operated from the state of the steering angle of zero, the angle of the axis of the steering damper to the axis of the attachment portion on the steering-side member side is gradually reduced. At this time, the swing angle of the steering damper to the swing limit is increased in comparison to the case where the axis of the steering damper forms a right angle with the axis of the attachment portion on the steering-side member side
According to the aspect of the present invention, in a state where the steering angle of the handlebar is zero, the axis of the steering damper forms an obtuse angle with the axis of an attachment portion on the steering-side member to which the steering damper is attached. With this configuration, when a spherical plain bearing is provided at the joint portion between the steering damper and the steering-side member, the available range of the swing angle of the spherical plain bearing is increased. The steering angle of the handlebar can thus be increased, while the steering angle has been restricted by the maximum swing angle of the spherical plain bearing.
Accordingly, it is possible to reduce the minimum turning radius of the vehicle, and to thus improve the handling of the vehicle.